It all depends. If you don't have a strong natural regional connection to the parent club but you are a big fan of the baseball team, you develop one. I'm sure back in the day there were people in Oklahoma and Oregon wearing Phillies caps. San Antonio Missions fans used to follow the Dodgers for sure. When the Houston Aeros hockey team was still around I knew people there who got into the Minnesota Wild, even though they were also already Dallas Stars fans (which is itself a quirk since Houston fans would normally never support a Dallas team).
But no doubt, the bigger the distance, the harder it is, and with casual fans it's a tougher sell. But with casual fans you're selling the overall entertainment experience, it just helps to also claim you have a certain quality of play from MLB prospects.
julio could say better than I but I don't imagine Williamsport is automatic/default Phillies territory - and if it is, the team has been part of the reason. Probably a decent chunk of Yankees fans too (as there are in SWB, even before the affiliation change, and still are Lehigh Valley). Pirates maybe not as much but it's about the same distance as Philly. Mostly, I assume, W'port is just a baseball town.